CC2640R2F: Elliptic Curve Diffie-Hellman - which file?

Hester Corne

Part Number: CC2640R2F
Other Parts Discussed in Thread: CC2642R

Hi,

I want to perform an ECDH key exchange on my application while the Bluetooth stack is running. I recently fell into the trap of using the driverlib Crypto library instead of the TI driver CryptoCC26XX library. Please could someone confirm which library I should be using for ECDH? I have found the following and am not sure which is appropriate:

ECDH.h at C:\ti\simplelink_cc2640r2_sdk_1_50_00_58\source\ti\drivers\ecdh
ECDHCC26X2.h at C:\ti\simplelink_cc2640r2_sdk_1_50_00_58\source\ti\drivers\ecdh\ECDHCC26X2.h
ECDHROMCC26XX.h at C:\ti\simplelink_cc2640r2_sdk_1_50_00_58\source\ti\blestack\common\cc26xx\ecc\ECCROMCC26XX.h

Is there a general rule for identifying which to use that I could apply in the future?

Thanks,

Hester

over 6 years ago

0 J Lindh over 6 years ago

TI__Guru 57865 points

Hi Hester,
I'm assigning this thread to the team handling driver support.

0 IUsedToBeARealPerson (M-W) over 6 years ago in reply to J Lindh

TI__Guru 58425 points

Hi Hester,

There is no driver support for ECDH. The TI Crypto driver provides you with AES-ECB and AES-CCM. There is ECC support in ROM (which is what the BLE stack uses, ECCROMCC26XX).

The ECDH files you linked to, ECDH.h and ECDHCC26X2.h is only for the new CC26X2/CC13X2 device family which would be the CC2642R in the case of BLE.

There is some additional driver support in the new 3.10 SDK as you can see here:

dev.ti.com/.../node

ECDH is however still limited to the X2 family.

As a general rule on which drivers you should use, I would recommend to first look at the TI Drivers (the side I linked to) and see if that covers it. If not, you might need to look at the driverlib to see if there is any APIs there available for what you want to do.

0 Hester Corne over 6 years ago in reply to IUsedToBeARealPerson (M-W)

Intellectual 790 points

Hi M-W,

Thanks for your response. Just to confirm, is it safe to use the ECC support in ROM for my own ends while the BLE stack is running? Is there anything I should be careful of in terms of timing?

0 IUsedToBeARealPerson (M-W) over 6 years ago in reply to Hester Corne

TI__Guru 58425 points

Hi Hester,

You should be able to use the BLE stack ECCROMCC26XX implementation as this should be reentrant safe.

0 IUsedToBeARealPerson (M-W) over 6 years ago in reply to Hester Corne

TI__Guru 58425 points

Hi Hester,

Please also note that SDK version 1.50 is no longer valid for BT SIG certification. We recommend using the new SDK 3.10 for developing new products.

0 Hester Corne over 6 years ago in reply to IUsedToBeARealPerson (M-W)

Intellectual 790 points

Hi M-W,

Please can you clarify exactly what that means? We were planning to go through the Bluetooth SIG qualification process here. Is this the same as "certification"? We were advised by your colleague a few weeks ago that version 1.50 of the SDK would be re-certified with a new QDID but it sounds like that may not be the case?

If it is the case that version 1.50 is no longer supported, we will have to move over to a later version. My understanding is that this will require more flash space because the part comes with the old version in ROM. Does the part come with a later SDK in ROM? Will it in the near future?

Thanks,

Hester

0 IUsedToBeARealPerson (M-W) over 6 years ago in reply to Hester Corne

TI__Guru 58425 points

Hi Hester,

Hopefully this thread can provide further update on the issue:

https://e2e.ti.com/support/wireless-connectivity/bluetooth/f/538/p/797957/2952310#2952310

As for migrating to a newer SDK, it is correct that this might come at the cost of some extra flash due to patches and bug fixes. There is no updates to the ROM to account for the fixes (and thus, the possible increase in flash consumption).

Bluetooth®︎

Bluetooth forum

CC2640R2F: Elliptic Curve Diffie-Hellman - which file?